1. Field of the Invention
This invention relates to a process of manufacturing a friction ring for use in a clutch or brake, which friction ring comprises a friction lining provided on at least one peripheral surface of a conical or cylindrical carrying ring, which has been formed from a flat sheet metal blank after a coating comprising a powder mixture has been formed on the flat sheet metal blank.
2. Description of the Prior Art
To permit a simple manufacture of friction rings which are intended for use in clutches or brakes and comprise a friction lining which has been sinter-bonded to the carrying ring, it has been disclosed in Austrian Patent Specification 385,826 to plank the carrying ring from flat sheet metal and to provide said carrying ring while it is still flat with a sinter-bonded friction lining on at least one of its surfaces which are intended to form the conical or cylindrical peripheral surfaces and subsequently to shape the flat carrying ring to the desired conical or cylindrical shape between the female die and punch of a shaping tool. But the sintered friction lining cannot be shaped together with the sheet metal ring unless the sintered friction lining has a sufficient ductility. This requirement imposes limits as regards the composition which may be selected for the sintered friction lining. For this reason it is usual to use sintered friction linings which comprise non-ferrous heavy metals, which in contact with transmission oils having a high additive content, e.g., tend to form sulfides, which adversely affect the performance of the friction lining. On the other hand, the ductility requirement precludes a decrease of the non-ferrous heavy metal content of the friction lining in favor of other metals, such as iron.